At present, web services matching is primarily based on functional aspects. For example, a service client might want to specify attributes such as response time, security level, price, etc., in addition to the desired functional capabilities when searching for a service. Moreover, as a consequence of the rapid growth of mobile web services, the consumer now faces the question of how to select the most appropriate service from a variety of service providers. In such a scenario, QoS (quality of service) can serve as a key differentiator among service providers. Moreover, when a mobile web service provider offers services to a large number of consumers, it has to accommodate the diverse characteristics and needs of its consumers, and one way to address this issue is to offer web services with different QoS.
There exists a variety of research works on QoS-aware web services discovery, and they tend to focus solely on fulfilling the requirements of either the client or the provider. However, the interests of the provider and client are not equivalent. The provider's goal is to maximize its profit, and one way to achieve this is by minimizing its resource cost. On the other, the client's selection is determined by their own requirements which do not always reflect the real resource cost of the provider. This is particularly important to conserve resource consumption for both service client and provider in addition to fulfilling the client requirements, since system resources in a mobile environment, such as wireless network bandwidth, are precious.